Position Problem/Stagger Animation

this. And i am almost did it, but i have problem. This is how i try to achieve this effect.
1. Create "shatter" pattern in Illustrator.
2. Export pattern. Choke edges for autotrace.
3. Autotrace.
4. Use mask_to_layers script. Tune masks for nice cuts without holes.
And now we need to animate this "particles". We can animate this with rotate or opacity, shift layers, animate camera. And we get very cool effect very similiar to this. But how we can animate particle positions? Cause if we just copy keyframes all layers goes to one dot(cause we copy exact numbers). We can animate position with null parenting(and we get our original position), but we cant stagger animation with this method. How we can copy/paste position animation pattern and saving original layer positions? I read den ebberts trails article, and still dont get this effect. I know this effect can be done without expressions, cause i seen project file with same effects and in this project just bunch of layers with same animation on every layer, but every layer has unique position(same animation same keyframes but with offset for assembly look and when we look on this layers without stagger its just solid plane with simple animation). How we can copy/paste position animation depending on original layer position? Maybe fancy script exist for this? Sorry for bad english, i hope you get my problem.